KR20080024285A - Liquid crystal composition and liquid crystal display comprising the same - Google Patents

Abstract

The present invention includes a first class comprising a liquid crystal compound having at least two fluorine atoms, and a second class comprising a liquid crystal compound without one fluorine atom or a fluorine atom, wherein the first class is represented by the formula (I ) And (II), the second class relates to a liquid crystal composition comprising at least one of liquid crystal compounds represented by formulas (III) and (IV) and a liquid crystal display device comprising the same .

Liquid crystal composition, dielectric anisotropy, refractive index anisotropy, line afterimage

Description

Liquid crystal composition and a liquid crystal display including the same {LIQUID CRYSTAL COMPOSITION AND LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a layout view of a common electrode panel for a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 3 is a layout view of a liquid crystal display including the thin film transistor array panel of FIG. 1 and the common electrode panel of FIG. 2.

4 and 5 are cross-sectional views of the liquid crystal display of FIG. 3 taken along lines IV-IV and V-V, respectively.

<Description of Drawing>

3: liquid crystal layer 310: liquid crystal molecules

11, 21: alignment film 12, 22: polarizer

81, 82: contact auxiliary member 83: holding electrode wire connecting leg

91, 92a, 92b, 71, 72a, 72b: incision

100, 200: display panel 110, 210: insulating substrate

121: gate line 124: gate electrode

129: end portion of gate line 131: sustain electrode line

133a-133d: sustain electrode 140: gate insulating film

151 and 154: semiconductors 161, 163 and 165: ohmic contact members

171: data line 173: source electrode

175: drain electrode 179: end of data line

180: protective film 183a, 183b, 185: contact hole

191: pixel electrode

220: light blocking member 230: color filter

250: overcoat 270: common electrode

The present invention relates to a liquid crystal composition and a liquid crystal display including the same.

Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. The liquid crystal display includes two display panels on which an electric field generating electrode is formed and a liquid crystal layer interposed therebetween, and determines a direction of liquid crystal molecules of the liquid crystal layer by generating an electric field in the liquid crystal layer by applying a voltage to the electric field generating electrode. And transmittance of light passing through the liquid crystal layer.

In liquid crystal displays, liquid crystals are very important for controlling a light transmittance to obtain a desired image. In particular, as the use of the liquid crystal display device is diversified, various characteristics such as low voltage driving, high voltage holding ratio (VHR), wide viewing angle characteristics, wide operating temperature range, and high speed response are required.

The liquid crystal layer includes a liquid crystal composition in which various kinds of liquid crystal components are mixed in order to satisfy these various characteristics.

However, since a liquid crystal composition contains many types of expensive liquid crystal components, these cost burden is large. When some of the liquid crystal components of the liquid crystal composition are subtracted in order to lower the material cost, some characteristics of the liquid crystal may be poor, which may affect the reliability of the liquid crystal composition.

On the other hand, the liquid crystal layer contains a large amount of ion impurity in addition to the liquid crystal composition. These ionic impurities may be lateral transported along the electric field generated in the liquid crystal layer and concentrated at a specific portion such as the boundary of the field generating electrode. In this case, the portion where the ion impurities are concentrated may be recognized as a residual image from the outside.

Accordingly, the technical problem to be achieved by the present invention is to solve this problem, while maintaining the reliability of the liquid crystal component while reducing the cost of the liquid crystal material. Furthermore, the afterimage of the liquid crystal display device is improved.

A liquid crystal composition according to an embodiment of the present invention includes a first class comprising a liquid crystal compound having at least two fluorine atoms, and a second class including a single fluorine atom or a liquid crystal compound having no fluorine atoms, The first class is liquid crystal compounds represented by formulas (I) and (II):

Wherein said second class is a liquid crystal compound represented by formulas (III) and (IV):

The liquid crystal compound represented by Formulas (I) and (II) includes at least one of R ₁ to R _4, which is one of alkyl groups or alkoxy groups having 1 to 10 carbon atoms, and the above formula (III) And liquid crystal compounds represented by (IV) have R ₅ to R ₈ as one of alkyl groups or alkoxy groups having 1 to 10 carbon atoms as end groups.

A liquid crystal display according to an exemplary embodiment of the present invention includes a pair of electric field generating electrodes formed on at least one of a first substrate, a second substrate facing the first substrate, the first substrate, and the second substrate; And a liquid crystal layer sandwiched between the first substrate and the second substrate, wherein the liquid crystal layer has a first class comprising a liquid crystal compound having at least two fluorine atoms, and one fluorine atom or a fluorine atom. And a second class comprising non-liquid liquid crystal compounds, the first class comprising liquid crystal compounds represented by formulas (I) and (II), wherein the second class is represented by formulas (III) and (IV) It includes a liquid crystal composition containing at least one of the liquid crystal compound.

Hereinafter, a liquid crystal composition according to an embodiment of the present invention will be described.

The liquid crystal composition includes various kinds of liquid crystal compounds having different physical properties.

The liquid crystal comprises a core group constituting the central axis and a terminal group and / or a lateral group connected thereto.

The central portion may include one or more cyclic compounds selected from phenyl groups, cyclohexyl groups, and heterocycles.

Terminal groups and side chain groups may include an alkyl group, an alkoxy group, a non-polar group such as an alkenyl group or a polar group such as a fluorine atom. The physical properties vary depending on the terminal groups and the side chain groups.

The liquid crystal composition according to the exemplary embodiment of the present invention is a liquid crystal compound exhibiting dielectric anisotropy (hereinafter referred to as a 'polar compound') and a liquid crystal compound having no dielectric anisotropy (hereinafter referred to as a 'neutral compound'). ).

Polar compounds exhibit dielectric anisotropy and refractive index anisotropy and have at least two fluorine atoms (F) in the side chain.

The polar compound may comprise a liquid crystal compound represented by the following formulas (I), (II), (V) and (VI), respectively:

R ₁ to R ₄ and R ₉ to R ₁₂ may be the same as or different from each other, and may have an alkyl group or an alkoxy group having 1 to 10 carbon atoms, respectively.

The liquid crystal compound represented by the formula (I) is preferably contained in about 20 to 40% by weight relative to the total content of the liquid crystal composition, and the liquid crystal compound represented by the formula (II) is about 1 to the total content of the liquid crystal composition It is preferably contained in 15% by weight. In addition, the liquid crystal compounds represented by the formulas (V) and (VI) are preferably contained in 40% by weight and 20% by weight or less based on the total content of the liquid crystal composition, respectively.

The liquid crystal compounds represented by the formulas (V) and (VI), respectively, are materials having high dielectric anisotropy and refractive index anisotropy, but are relatively expensive so that the cost of the liquid crystal material increases when its content is increased.

In this invention, the liquid crystal compound represented by General formula (II) is included as a component which can replace such an expensive liquid crystal component. The liquid crystal compound represented by the formula (II) exhibits high dielectric anisotropy and refractive index anisotropy at a relatively low price.

Therefore, instead of reducing the content of the liquid crystal compound represented by the formulas (V) and (VI), respectively, about 1 to 15% by weight, more preferably about 5 to 12% by weight of the liquid crystal compound represented by the formula (II) By containing in%, the dielectric anisotropy and refractive index anisotropy of the same level as before are maintained.

The polar compound may be contained in about 10 to 90% by weight relative to the total content of the liquid crystal composition.

The neutral compound is a component for properly maintaining the viscosity of the liquid crystal while having refractive anisotropy, and may include a compound having one fluorine atom or no fluorine atom in the side chain.

The neutral compound may comprise at least one selected from formulas (III), (IV), (VII), (VIII), (IX), (X) and (XI):

R ₅ to R ₈ and R ₁₃ to R ₂₂ may be the same as or different from each other, and may include an alkyl group, an alkoxy group or an alkenyl group having 1 to 10 carbon atoms, respectively.

The liquid crystal compounds represented by the formulas (III) and (IV) are preferably contained in an amount of 15% by weight or less based on the total content of the liquid crystal composition, and are represented by the formulas (VII), (VIII), (IX), (X) and The liquid crystal compound represented by (XI) is preferably contained in 20% by weight, 30% by weight, 25% by weight, 20% by weight and 10% by weight or less based on the total content of the liquid crystal composition.

Among them, the liquid crystal compounds represented by the formulas (III) and (IV) are relatively inexpensive and exhibit high refractive index anisotropy, and when the content of the liquid crystal compounds represented by the relatively expensive formulas (V) and (VI) is reduced, respectively. The refractive index anisotropy can be compensated for.

The neutral compound preferably contains about 10 to 90% by weight relative to the total content of the liquid crystal composition.

In this case, when at least one of R ₅ to R ₈ and R ₁₃ to R ₂₂ includes an alkenyl group, the compound containing the alkenyl group is preferably contained in about 7% by weight or less based on the total content of the liquid crystal composition, It is more preferable when it does not contain an alkenyl group.

As such, according to one embodiment of the present invention, the content of the neutral compound having an alkenyl group in the terminal group is limited. That is, the liquid crystal composition does not contain a neutral compound having an alkenyl group in the terminal group, or even if it contains it, it is contained in about 7% by weight or less based on the total content of the liquid crystal composition.

When the alkenyl group is included in the terminal group of the neutral compound, the double bond position of the alkenyl group may be a reaction site of an ionic impurity. Accordingly, the ionic impurities are bonded to the terminal groups of the neutral compound and remain as is even after the preparation of the liquid crystal composition. When the ionic impurities move in a plane along the electric field generated in the liquid crystal display when the liquid crystal display is driven, they are positioned at a specific part such as the boundary of the field generating electrode. Triggered.

Therefore, in the present invention, by limiting the content of the neutral compound having an alkenyl group in the terminal group, it is possible to reduce the reaction with the ionic impurities, thereby reducing the change in refractive index anisotropy of the liquid crystal composition by the ionic impurities, the afterimage characteristic Can be improved.

Afterimage is evaluated by the following method.

First, a test display panel including two substrates on which an electric field generating electrode is formed and a liquid crystal layer interposed therebetween is prepared. A plurality of pixels are arranged on the test display panel. Some pixels arranged alternately horizontally and vertically among the plurality of pixels are displayed with black and white are displayed with the remaining pixels to display a grid-shaped black / white pattern. Then, after a certain time, the black / white marks are removed, and the entire test panel is changed from black to white with a uniform gradation to check whether a line-shaped stain is visible at the boundary of each pixel. The time taken until the line-shaped stain is visually recognized (hereinafter, referred to as a 'line afterimage expression time') is measured. The line afterimage expression time is a criterion indicating how long the liquid crystal display device can be driven without line afterimage, and the higher the afterimage expression time is, the better the afterimage characteristic is.

As a result of the experiment, when there is no neutral compound having an alkenyl group at the terminal group, the afterimage expression time was found to be about 3000 hours. In contrast, as the content of the neutral compound having an alkenyl group in the terminal group increases, the afterimage expression time is significantly shorter, especially when the content of the neutral compound having an alkenyl group in the terminal group exceeds about 7% by weight. The time was found to fall below 2000 hours.

As such, according to one embodiment of the present invention, when the neutral compound having an alkenyl group in the terminal group is contained in about 7% by weight or less with respect to the total content of the liquid crystal composition, it is possible to secure a linear afterimage expression time of 2000 hours or more. .

The liquid crystal composition according to the exemplary embodiment of the present invention described above satisfies all of the dielectric anisotropy of about -2.7 to -5.8, the refractive index anisotropy of 0.075 to 0.109, and the rotational viscosity of 87 to 165 mPa · s by including the above liquid crystal components. It was confirmed that.

Therefore, even in the case of including a relatively inexpensive liquid crystal component in a proper ratio in place of the existing expensive liquid crystal component, it is possible to secure an appropriate dielectric anisotropy and refractive index anisotropy.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right over" but also when there is another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle. Next, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention, FIG. 2 is a layout view of a common electrode display panel for a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. FIG. 4 is a layout view of a liquid crystal display including the thin film transistor array panel and the common electrode display panel of FIG. 2, and FIGS. 4 and 5 are cross-sectional views of the liquid crystal display of FIG. 3 taken along lines IV-IV and VV, respectively.

1 to 5, a liquid crystal display according to an exemplary embodiment of the present invention includes a thin film transistor array panel 100 and a common electrode panel 200 facing each other and between the two display panels 100 and 200. The liquid crystal layer 3 is included.

First, the thin film transistor array panel 100 will be described with reference to FIGS. 1, 3, 4, and 5.

A plurality of gate lines 121 and a plurality of storage electrode lines 131 are formed on an insulating substrate 110 made of transparent glass or plastic.

The gate line 121 transmits a gate signal and mainly extends in a horizontal direction. Each gate line 121 includes a plurality of gate electrodes 124 protruding upwards and a wide end portion 129 for connection with another layer or an external driving circuit. A gate driving circuit (not shown) for generating a gate signal may be mounted on a flexible printed circuit film (not shown) attached to the substrate 110 or directly mounted on the substrate 110, It may be integrated into the substrate 110. When the gate driving circuit is integrated on the substrate 110, the gate line 121 may extend to be directly connected to the gate driving circuit.

The storage electrode line 131 receives a predetermined voltage and has a stem line extending substantially in parallel with the gate line 121 and a plurality of first, second, third and fourth storage electrodes 133a, 133b, 133c, 133d) a set and a plurality of connections 133e. Each of the storage electrode lines 131 is positioned between two adjacent gate lines 121, and the stem line is closer to the upper side of the two gate lines 121.

The first and second storage electrodes 133a and 133b extend in the vertical direction and face each other. The first storage electrode 133a has a fixed end connected to the stem line and a free end opposite thereto, and the free end includes a protrusion. The third and fourth storage electrodes 133c and 133d extend obliquely from the center of the first storage electrode 133a to the lower end and the upper end of the second storage electrode 133b. The connecting portion 133e is connected between adjacent sets of sustain electrodes 133a to 133d. However, the shape and arrangement of the storage electrode line 131 may be modified in various ways.

The gate line 121 and the storage electrode line 131 may be formed of aluminum-based metal such as aluminum (Al) or aluminum alloy, silver-based metal such as silver (Ag) or silver alloy, copper-based metal such as copper (Cu) or copper alloy, or molybdenum ( It may be made of low resistance conductors such as molybdenum-based metals such as Mo) and molybdenum alloys, chromium (Cr), tantalum (Ta), and titanium (Ti). However, they may have a multilayer structure including two conductive films (not shown) having different physical properties.

Side surfaces of the gate line 121 and the storage electrode line 131 are inclined with respect to the surface of the substrate 110, and the inclination angle is preferably about 30 ° to about 80 °.

A gate insulating layer 140 made of silicon nitride (SiNx) or silicon oxide (SiOx) is formed on the gate line 121 and the storage electrode line 131.

A plurality of linear semiconductors 151 made of hydrogenated amorphous silicon (hereinafter referred to as a-Si) or polysilicon are formed on the gate insulating layer 140. The linear semiconductor 151 mainly extends in the longitudinal direction and includes a plurality of projections 154 extending toward the gate electrode 124.

A plurality of linear and island ohmic contacts 161 and 165 are formed on the semiconductor 151. The ohmic contacts 161 and 165 may be made of a material such as n + hydrogenated amorphous silicon in which n-type impurities such as phosphorus are heavily doped, or may be made of silicide. The linear ohmic contact 161 has a plurality of protrusions 163, and the protrusion 163 and the island-type ohmic contact 165 are paired and disposed on the protrusion 154 of the semiconductor 151.

Side surfaces of the semiconductor 151 and the ohmic contacts 161 and 165 are also inclined with respect to the surface of the substrate 110, and the inclination angle is about 30 ° to 80 °.

On the ohmic contacts 161 and 165 and the gate insulating layer 140, a plurality of data lines 171, a plurality of drain electrodes 175, and a plurality of isolated metal pieces ( 178 is formed.

The data line 171 transmits a data signal and mainly extends in a vertical direction to intersect the gate line 121, the stem line of the storage electrode line 131, and the connecting portion 133e. Each data line 171 includes a wide end portion 179 for connecting a plurality of source electrodes 173 extending toward the gate electrode 124 with another layer or an external driving circuit. A data driving circuit (not shown) for generating a data voltage is mounted on a flexible printed circuit film (not shown) attached to the substrate 110, directly mounted on the substrate 110, or integrated in the substrate 110. Can be. When the data driving circuit is integrated on the substrate 110, the data line 171 may be extended to be directly connected to the data driving circuit.

The drain electrode 175 is separated from the data line 171 and faces the source electrode 173 around the gate electrode 124. Each drain electrode 175 has one wide end and the other end having a rod shape, and the rod end portion is partially surrounded by the source electrode 173.

One gate electrode 124, one source electrode 173, and one drain electrode 175 together with the protrusion 154 of the semiconductor 151 form one thin film transistor (TFT). A channel of the transistor is formed in the protrusion 154 between the source electrode 173 and the drain electrode 175.

The isolated metal piece 178 is positioned on the gate line 121 near the first storage electrode 133a.

The data line 171, the drain electrode 175, and the isolated metal piece 178 may be made of a low resistance conductor like the gate line 121.

The data line 171, the drain electrode 175, and the isolated metal piece 178 may also be inclined at an inclination angle of about 30 ° to about 80 ° with respect to the surface of the substrate 110.

The ohmic contacts 161 and 165 exist only between the semiconductor 151 below and the data line 171 and the drain electrode 175 thereon, and lower the contact resistance therebetween.

A passivation layer 180 is formed on the data line 171, the drain electrode 175, the isolated metal piece 178, and the exposed semiconductor 151. The passivation layer 180 may be made of an inorganic insulator or an organic insulator, and may have a flat surface. Examples of the inorganic insulator include silicon nitride (SiNx) and silicon oxide (SiOx). The organic insulator may have photosensitivity and the dielectric constant is preferably about 4.0 or less. However, the passivation layer 180 may have a double layer structure of the lower inorganic layer and the upper inorganic layer so as not to damage the exposed portion of the semiconductor 154 while maintaining excellent insulating properties of the organic layer.

A plurality of pixel electrodes 191, a plurality of overpasses 83, and a plurality of contact assistants 81 and 82 are formed on the passivation layer 180. They may be made of a transparent conductive material such as ITO or IZO or a reflective metal such as aluminum, silver, chromium or an alloy thereof.

The pixel electrode 191 is physically and electrically connected to the drain electrode 175 through the contact hole 185 and receives a data voltage from the drain electrode 175. The pixel electrode 191 to which the data voltage is applied is generated between the two electrodes 191 and 270 by generating an electric field together with the common electrode 270 of the other display panel 200 to which the common voltage is applied. The direction of the liquid crystal molecules of the liquid crystal layer 3 is determined. The polarization of light passing through the liquid crystal layer 3 varies according to the direction of the liquid crystal molecules determined as described above. The pixel electrode 191 and the common electrode 270 form a capacitor (hereinafter, referred to as a 'liquid crystal capacitor') to maintain an applied voltage even after the thin film transistor is turned off.

The pixel electrode 191 overlaps the storage electrode line 131 including the storage electrodes 133a-133d. A capacitor formed by the pixel electrode 191 and the drain electrode 175 electrically connected to the pixel electrode 191 overlapping the storage electrode line 131 is called a storage capacitor, and the storage capacitor enhances the voltage holding capability of the liquid crystal capacitor.

Each pixel electrode 191 has four peripheral sides substantially parallel to the gate line 121 or the data line 171 and has a substantially rectangular shape in which four corners are chamfered. The hypotenuse of the pixel electrode 191 forms an angle of about 45 degrees with respect to the gate line 121. A central cutout 91, a lower cutout 92a, and an upper cutout 92b are formed in the pixel electrode 191, and the pixel electrode 191 includes a plurality of regions by the cutouts 91-92b. It is divided into partitions. The cutouts 91-92b are almost inverted symmetric with respect to an imaginary transverse centerline that bisects the pixel electrode 191.

The lower and upper cutouts 92a and 92b extend obliquely from the right side to the left side of the pixel electrode 191 and overlap the third and fourth sustain electrodes 133c and 133d, respectively. The lower and upper cutouts 92a and 92b are positioned at the lower half and the upper half with respect to the horizontal center line of the pixel electrode 191, respectively. The lower and upper cutouts 92a and 92b extend perpendicular to each other at an angle of about 45 degrees with respect to the gate line 121.

The central cutout 91 extends along the horizontal centerline of the pixel electrode 191 and has an inlet at the right side thereof. The inlet of the central incision 91 has a pair of hypotenuses substantially parallel to the lower incision 92a and the upper incision 92b, respectively. The central cutout 91 includes a horizontal portion and a pair of diagonal lines connected thereto. The horizontal portion extends shortly along the horizontal center line of the pixel electrode 191, and the pair of diagonal portions substantially extends toward the right side of the pixel electrode 191 from the horizontal portion with the lower cutout 92a and the upper cutout 92b, respectively. Stretched side by side.

Accordingly, the lower half of the pixel electrode 191 is divided into two regions by the lower cutout 92a, and the upper half is also divided into two regions by the upper cutout 92b. In this case, the number of regions or the number of cutouts may vary depending on design factors such as the size of the pixel electrode 191, the ratio of the lengths of the horizontal and vertical sides of the pixel electrode 191, the type and characteristics of the liquid crystal layer 3, and the like. .

The connecting leg 83 crosses the gate line 121 and exposes the first portion of the storage electrode line 131 and the first holding portion through the contact holes 183a and 183b positioned opposite to each other with the gate line 121 interposed therebetween. The electrode 133a is connected to the exposed end of the free end. The storage electrode lines 131 including the storage electrodes 133a and 133b may be used together with the connection legs 83 to repair defects in the gate line 121, the data line 171, or the thin film transistor.

The contact auxiliary members 81 and 82 are connected to the end portion 129 of the gate line 121 and the end portion 179 of the data line 171 through the contact holes 181 and 182, respectively. The contact auxiliary members 81 and 82 compensate for and protect the adhesion between the end portion 129 of the gate line 121 and the end portion 179 of the data line 171 and the external device.

Next, the common electrode display panel 200 will be described with reference to FIGS. 2 to 4.

A light blocking member 220 is formed on an insulating substrate 210 made of transparent glass or plastic. The light blocking member 220 is called a black matrix and blocks light leakage between the pixel electrodes 191. The light blocking member 220 has a plurality of openings 225 facing the pixel electrode 191 and having substantially the same shape as the pixel electrode 191. However, the light blocking member 220 may include a portion corresponding to the gate line 121 and the data line 171 and a portion corresponding to the thin film transistor.

A plurality of color filters 230 is also formed on the substrate 210. The color filter 230 is mostly present in an area surrounded by the light blocking member 230, and may extend in the vertical direction along the column of the pixel electrodes 191. Each color filter 230 may display one of three primary colors such as red, green, and blue.

An overcoat 250 is formed on the color filter 230 and the light blocking member 220. The overcoat 250 may be made of an (organic) insulator, which prevents the color filter 230 from being exposed and provides a flat surface. The overcoat 250 may be omitted.

The common electrode 270 is formed on the overcoat 250. The common electrode 270 is made of a transparent conductor such as ITO or IZO, and the plurality of cutouts 71, 72a, and 72b are formed on the common electrode 270.

One set of cutouts 71-72b faces one pixel electrode 191 and includes a central cutout 71, a lower cutout 72a, and an upper cutout 72b. Each of the cutouts 71-72b is disposed between adjacent cutouts 91-92b of the pixel electrode 191 or between cutouts 92a and 92b and the hypotenuse of the pixel electrode 191. In addition, each cutout 71-72b includes at least one diagonal line extending substantially in parallel with the lower cutout 92a or the upper cutout 92b of the pixel electrode 191. The cutouts 71-72b are almost inverted symmetric with respect to the horizontal center line of the pixel electrode 191.

The lower and upper cutouts 72a and 72b respectively include an oblique section, a horizontal section and a vertical section. The diagonal portion extends from the upper side or the lower side of the pixel electrode 191 to the left side. The horizontal part and the vertical part extend from each end of the oblique part along the sides of the pixel electrode 191 while overlapping the sides and form an obtuse angle with the oblique part.

The central cutout 71 includes a central transverse portion, a pair of oblique portions and a pair of longitudinal longitudinal portions. The central horizontal portion extends from the left side of the pixel electrode 191 to the right along the horizontal center line of the pixel electrode 191. The pair of oblique portions extends in parallel with the lower and upper cutouts 72a and 72b while forming an obtuse angle with the central horizontal portion from the end of the central horizontal portion toward the right side of the pixel electrode 191. The vertical longitudinal portion extends along the right side of the pixel electrode 191 from the end of the diagonal line and overlaps the right side, and forms an obtuse angle with the diagonal line.

The number of the cutouts 71-72b may also vary according to design factors, and the light blocking member 220 may overlap the cutouts 71-72b to block light leakage near the cutouts 71-72b.

When a common voltage is applied to the common electrode 270 and a data voltage is applied to the pixel electrode 191, an electric field almost perpendicular to the surfaces of the display panels 100 and 200 is generated. In response to the electric field, the liquid crystal molecules attempt to change their long axis to be perpendicular to the direction of the electric field.

The cutouts 71-72b and 91-92b of the field generating electrodes 191 and 270 and the sides of the pixel electrode 191 distort the electric field to create horizontal components that determine the inclination direction of the liquid crystal molecules. The horizontal component of the electric field is substantially perpendicular to the sides of the cutouts 71-72b and 91-92b and the sides of the pixel electrode 191.

Referring to FIG. 3, one set of cutouts 71-72b and 91-92b divides the pixel electrode 191 into a plurality of sub-areas, and each sub-region is a main portion of the pixel electrode 191. It has two primary edges that form an oblique side. The periphery of each subregion forms about 45 degrees with the polarization axis of the polarizers 12 and 22, in order to maximize the light efficiency.

Most of the liquid crystal molecules on each subregion are inclined in a direction perpendicular to the periphery thereof, and thus, the inclination directions are approximately four directions. As described above, when the liquid crystal molecules are inclined in various directions, the reference viewing angle of the liquid crystal display is increased.

The shape and arrangement of the cutouts 71-72b and 91-92b can be variously modified.

At least one cutout 71-72b, 91-92b may be replaced by a protrusion (not shown) or depression (not shown). The protrusions may be made of organic or inorganic materials and may be disposed above or below the field generating electrodes 191 and 270.

Alignment layers 11 and 21 are coated on inner surfaces of the display panels 100 and 200, and they may be vertical alignment layers.

Polarizers 12 and 22 are provided on the outer surfaces of the display panels 100 and 200, and the polarization axes X and Y of the two polarizers 12 and 22 are orthogonal to each other, and the diagonal cutouts 92a and 92b are provided. ) And an oblique angle of the incisions 71-72b. In the case of a reflective liquid crystal display, one of the two polarizers 12 and 22 may be omitted.

The liquid crystal display according to the exemplary embodiment of the present invention may further include a phase retardation film (not shown) for compensating for the delay of the liquid crystal layer 3. The liquid crystal display may also include a polarizer 12 and 22, a phase retardation film, display panels 100 and 200, and a backlight unit (not shown) for supplying light to the liquid crystal layer 3.

The liquid crystal layer 3 has negative dielectric anisotropy, and the liquid crystal molecules of the liquid crystal layer 3 are aligned such that their major axes are substantially perpendicular to the surfaces of the two display panels 100 and 200 in the absence of an electric field. Therefore, incident light does not pass through the quadrature polarizers 12 and 22 and is blocked.

As described above, the liquid crystal layer 3 is composed of a liquid crystal composition containing a polar compound exhibiting dielectric anisotropy and a neutral compound exhibiting no dielectric anisotropy.

Description of the polar compound and the neutral compound is the same as described above, and will be omitted here.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

By adjusting the liquid crystal component and the composition ratio, the cost of the liquid crystal material can be lowered as compared with the existing liquid crystal composition while maintaining physical properties such as dielectric anisotropy, refractive index anisotropy, and rotational viscosity. In addition, an afterimage of the liquid crystal display may be improved.

Claims (16)

A first class comprising a liquid crystal compound having at least two fluorine atoms, and Second class comprising one fluorine atom or a liquid crystal compound having no fluorine atom Including, The first class is liquid crystal compounds represented by formulas (I) and (II):

Including; The second class comprises at least one of the liquid crystal compounds represented by the formulas (III) and (IV),

The liquid crystal compounds represented by formulas (I) and (II) have R ₁ to R _{4, which} are one of alkyl groups or alkoxy groups having 1 to 10 carbon atoms, as end groups, and are represented by formulas (III) and (IV). The liquid crystal compound has R ₅ to R ₈ as one of alkyl groups, alkoxy groups and alkenyl groups having 1 to 10 carbon atoms as end groups. Liquid crystal composition. In claim 1, The first class and the second class of the liquid crystal composition is contained in 10 to 90% by weight relative to the total content of the liquid crystal composition. In claim 2, The liquid crystal compound represented by the formula (I) is contained in 20 to 40% by weight based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (II) is contained in 1 to 15% by weight based on the total content of the liquid crystal composition, The liquid crystal compounds represented by Formulas (III) and (IV) are each contained in an amount of 15 wt% or less, based on the total content of the liquid crystal composition. Liquid crystal composition. In claim 1, The first class is a liquid crystal compound represented by the formulas (V) and (VI):

At least one of, Formula (V) and a liquid crystal compound which is represented by (VI) is with one of R ₉ to R ₁₂ in the number of one to ten carbon alkyl group or alkoxy group as a terminal group Liquid crystal composition. In claim 4, The liquid crystal compound represented by the formula (V) is contained in 40% by weight or less based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (VI) is contained in 20% by weight or less based on the total content of the liquid crystal composition Liquid crystal composition. In claim 5, The second class is liquid crystal compounds represented by formulas (VII) to (XI):

At least one of, The liquid crystal compounds represented by the formulas (VII) and (XI) have R ₁₃ to R ₂₂ which is one of an alkyl group having 1 to 10 carbon atoms, an alkoxy group and an alkenyl group as terminal groups. Liquid crystal composition. In claim 6, The liquid crystal compound represented by the formula (VII) is contained in 20% by weight or less based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (VIII) is contained in 30% by weight or less based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (IX) is contained in 25% by weight or less based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (X) is contained in 20% by weight or less based on the total content of the liquid crystal composition, The liquid crystal compound represented by Chemical Formula (XI) is contained in 10% by weight or less based on the total content of the liquid crystal composition Liquid crystal composition. In claim 7, When the liquid crystal compound containing no alkenyl group in the terminal group in the second class is called a first subclass, and the liquid crystal compound containing alkenyl group is called a second subclass, the second subclass is the first subclass. A liquid crystal composition containing not more than 7% by weight based on the total content of the class and the second class. In claim 8, And wherein said liquid crystal composition does not comprise said second subclass. First substrate, A second substrate facing the first substrate, A pair of field generating electrodes formed on at least one of the first substrate and the second substrate, and A liquid crystal layer interposed between the first substrate and the second substrate Including, The liquid crystal layer is A first class comprising a liquid crystal compound having at least two fluorine atoms, and Second class comprising one fluorine atom or a liquid crystal compound having no fluorine atom Including, The first class is liquid crystal compounds represented by formulas (I) and (II):

Including; The second class is liquid crystal compounds represented by formulas (III) and (IV):

At least one of The liquid crystal compounds represented by formulas (I) and (II) have R ₁ to R _{4, which} are one of alkyl groups or alkoxy groups having 1 to 10 carbon atoms, as end groups, and are represented by formulas (III) and (IV). The liquid crystal compound to be used includes a liquid crystal composition having R ₅ to R ₈ as one of alkyl groups, alkoxy groups and alkenyl groups having 1 to 10 carbon atoms as end groups. Liquid crystal display. In claim 10, The liquid crystal compound represented by Formula (I) is contained in 20 to 40% by weight based on the total content of the liquid crystal composition, The liquid crystal compound represented by the formula (II) is contained in 1 to 15% by weight based on the total content of the liquid crystal composition, The liquid crystal compounds represented by the formulas (III) and (IV) are each contained in an amount of 15% by weight or less based on the total content of the liquid crystal composition. Liquid crystal display. In claim 10, When the liquid crystal compound containing no alkenyl group in the terminal group in the second class is called a first subclass, and the liquid crystal compound containing alkenyl group is called a second subclass, the second subclass is the first subclass. A liquid crystal display device containing not more than 7% by weight based on the total content of the class and the second class. In claim 12, And said liquid crystal composition does not comprise said second subclass. In claim 10, First and second signal lines crossing each other on the first substrate, and A thin film transistor connected to the first and second signal lines Liquid crystal display further comprising. The method of claim 14, And an inclination direction determining member configured to determine a direction in which the liquid crystal compound of the liquid crystal layer is inclined. The method of claim 15, The inclination direction determining member includes a cutout formed in the field generating electrode or a protrusion formed on the field generating electrode.

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